I recently saw a magician do a book routine that I am not familiar with. He had the spectator choose a book from a bag of about 5 familiar books while his back was turned. The spectator held the book behind their back and the magician was able to identify which one it was. And he was able to repeat this 3x. I wasn't sure if this might use something like Tony Averdni's Color Match sensors? The kicker was a prediction reveal on his Instagram bio on anyone's phone (i.e. Stranger App or kinda like but not really IG by Jake Janousky, Hydra, etc.). Anyone know which method is used for this? Thanks.